The present invention relates to the inspection of castings in a machine for continuous casting, particularly under conditions of heat emanating from the barely solidified skin of the casting.
In the past, visual inspection of a casting by experienced personnel has been common practice. The same is true with regard to solidified casting ingots; however, other inspection methods of cold ingots involve the utilization of ultrasonics, magnetic fields as they are varied by defects, chemical effects, or other metal checks. Not only does the ingot so inspected have to be cold (relatively speaking, the temperature should be lower than approximately 300.degree. C.), but the test piece should be stationary.
German printed patent application 29 11 578 discloses a system for optical inspection of a casting, using a supplemental light source and detecting particular reflection features which can be attributed to surface defects.
In a companion patent (Application Ser. No. 337,622, filed on Jan. 7, 1982, we have proposed a device for inspecting such a casting under utilization of an annular, cooled, two-part housing having an annular, inwardly directed gap across which slides (rotates) a short sleeve, leaving but a narrow gap for a revolving detector. The detector thus rotates about the casting passing through centrally in axial direction so that a helical inspection band (hypothetical) is inscribed. This particular inspection arrangement responds specifically to the radiation that emanates from the casting and permits the early detection of surface defects. Also, the geometry of the casting can be ascertained in this manner.